Characterization of the spermiation response, luteinizing hormone release and sperm quality in the American toad (Bufo americanus) and the endangered Wyoming toad (Bufo baxteri)

Abstract

Spermiation and LH release in response to several methods of LHRHadministration were assessed in the American toad(Bufo americanus), and the most successful method wastested in the endangered Wyoming toad (Bufo baxteri).Specific objectives were to: (1) compare spermiationresponses and plasma LH concentration after invasive and non-invasive LHRHtreatments; (2) evaluate sperm production in response todifferent LHRH dosages; (3) characterize the timing ofsperm release post LHRH treatment; and (4) assess spermquality (motility, viability, morphology and acrosomal status). Male Americantoads were administered 4 g LHRH by one of four routes:(1) intraperitoneal injection (IP);(2) subcutaneous injection (SQ);(3) dorsal dermis absorption (DDA); and(4) ventral dermis absorption (VDA). Aspermic urine onlywas collected from saline-treated controls and DDA animals. Several VDAanimals released spermic urine; however, all LHRH-injected toads releasedspermatozoa. IP animals produced higher sperm and LH concentrations than SQanimals. The spermiation response in animals treated IP with 1 g LHRH wassimilar to that in animals treated with 4 g, but lower LHRH dosages testedproduced inferior responses. Sperm production in responsive animals increasedover time during the 12-h sampling interval. Regardless of treatment, mostAmerican toad spermatozoa were motile, viable, and acrosome-intact. EndangeredWyoming toads were treated IP with 4 g LHRH, and spermic urine was collected.Although most spermatozoa were viable and acrosome-intact, a considerablepercentage possessed structurally abnormal heads. A single IP injection ofLHRH appears to be a reliable and safe method for controlling spermiation intoads and may be useful for assisting endangered amphibian propagation.